The major objective of this work is to isolate, purify and determine the structure of the anitumor alkaloids present in Catharanthus roseus and Rhazya stricta. The Madagascan plant Catharanthus roseus has been well studied, and several active antitumor principles have been isolated. However, a number of fractions containing alkaloids and exhibiting very high activity in vivo remain to be studied. The crude alkaloid mixtures will be separated initially by pH gradient techniques and subsequently by column chromatography, combined as appropriate and then evaluated biologically either in vivo or in vitro depending upon the activity of the original fraction. Isolated compounds will be identified by their mp, mass, UV and IR spectra, optical rotation and PMR and CMR spectra. Strture elucidation will be carried out by interpretation of these data, chemical correlation with known compounds and in particularly difficult cases by single crystal X-ray crystallography. All information on new, active dimeric indole alkaloids will be discussed with Professor J.P. Kutney of the University of British Columbia, for contemplation as candidates for synthesis and structure confirmation. The Asian plant Rhazya stricta is at a much earlier stage of development. Reports have indicated that extracts of this plant exhibit a marked leucopenic effect. The close botanical relationship of this genus and the genus Catharanthus in the family Apocynaceae makes this plant of considerable interest. It is expected that antitumor activity will be found in the alkaloid fraction of Rhazya stricta. If this is the case it will be fractionated in the same way as described above for Catharanthus roseus.